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Hasan A Yousef's questions

Martin Hope
Hasan A Yousef
Asked: 2023-09-09 02:58:54 +0800 CST
  • 5

我有以下代码：

const std = @import("std");

fn getTLVForValue(writer: anytype, tagNum: []const u8, tagValue: []const u8) !void {
    _ = try writer.write(tagNum);;
    _ = try writer.writeByte(@intCast(tagValue.len));
    _ = try writer.write(tagValue);
}

pub fn main() !void {
    var arena = std.heap.ArenaAllocator.init(std.heap.page_allocator);
    const allocator = arena.allocator();
    var qrCodeBuf = std.ArrayList(u8).init(allocator);
    defer qrCodeBuf.deinit();
    const writer = qrCodeBuf.writer();

    //1. Seller Name
    try getTLVForValue(writer, "01", "Bobs Basement Records");

    //2. VAT Registration
    try getTLVForValue(writer, "02", "312345678901233");

    //3. Time stamp
    try getTLVForValue(writer, "03", "12-12-2023");

    //4. tax Total
    try getTLVForValue(writer, "04", "1000");

    //5. Vat Total
    try getTLVForValue(writer, "05", "115");

    //6. Hashed XML
    try getTLVForValue(writer, "06", "dsds");

    //7. key
    try getTLVForValue(writer, "07", "125");

    //8. Signature
    try getTLVForValue(writer, "08", "dsfsd");

    std.debug.print("{any}\n", .{qrCodeBuf.items});

    std.debug.print("Hex string: {s}\n", .{std.fmt.fmtSliceHexUpper(qrCodeBuf.items)});
    // const hex = try std.fmt.allocPrint("{s}", .{std.fmt.fmtSliceHexUpper(qrCodeBuf.items)});

    const output_buffer = try allocator.alloc(u8, std.base64.standard.Encoder.calcSize(qrCodeBuf.items.len));
    defer allocator.free(output_buffer);
    const data = std.base64.standard.Encoder.encode(output_buffer, qrCodeBuf.items);
    std.debug.print("{s}\n", .{data});

    const decode_buf = try allocator.alloc(u8, try std.base64.standard.Decoder.calcSizeForSlice(data));
    try std.base64.standard.Decoder.decode(decode_buf, data);
    std.debug.print("{s}\n", .{decode_buf});
    std.debug.print("{}\n", .{std.zig.fmtEscapes(decode_buf)});

    try std.testing.expectEqualStrings(qrCodeBuf.items, decode_buf);
}

它给我的最终输出为：

01\x15Bobs Basement Records02\x0f31234567890123303\n12-12-202304\x04100005\x0311506\x04dsds07\x0312508\x05dsfsd

但在这里我得到的是不可打印的 ASCII 字符而不是数字，例如，我得到的\n不是10和\x15而是21等等，按照此处显示的映射。

我打开了任何替代选项来让函数getTLVForValue返回TLV - Tag - Length - Value，这样我就可以得到例如0103xxxx长度为 is3且 tagNum 为 的标签01。

我正在尝试编写一个代码来执行下面屏幕截图中解释的操作：

图像

zig